| 摘要 |
This application relates to channel quality indicator (CQI) feedback in a multi input multi output (MIMO) system. A receiver receives a signal which was transmitted using a precoding matrix W, and also receives the precoding matrix W over a control channel. The receiver passes the signal through a signal processing module, such as an MMSE MIMO equaliser or a RAKE receiver, whose impulse response can be represented by the matrix F. The receiver also estimates a preferred precoding matrix Wp which it feeds back to the transmitter for possible use for the next transmission, alongside a CQI value associated with Wp. What follows is an explanation of how this CQI is determined, according to the invention. The receiver uses the received signal to estimate a first effective channel G. G=FHW, where H is the MIMO channel matrix between transmitter and receiver. The receiver then estimates a second effective channel Gp=FHWP by transforming the estimate of the first effective channel G, using a transformation matrix T based on the precoding matrices W and Wp. |
